Currently, the methods used for assessing the quality of bypass operations may be seen as insufficient to correctly detect weaknesses of the bypass graft. Current methods may be based on simply using tactile senses, i.e. fingertips, for assessing whether the bypass vessel is properly attached. One problem that may arise is that the attached bypass vessel limits the flow of blood too much due to a narrowing at the joint between the vessel and the bypass vessel.
To avoid complications it would be desirable to be able to quickly and accurately determine the quality of the bypass vessel, e.g. to determine if the lumen of the bypass vessel is sufficiently large.
The paper “Intraoperative evaluation of coronary artery bypass graft anastomoses with high-frequency epicardial echocardiography: experimental validation and initial patient studies, L F Hiratzka, D D McPherson, W C Lamberth, Jr, B Brandt, 3d, M L Armstrong, E Schroder, M Hunt, R Kieso, M D Megan and P K Tompkins, in Circulation 1986; 73; 1199-1205, © 1986 American Heart Association. ISSN: 0009-7322” discloses a method where a high-frequency epicardial echocardiography performed intraoperatively could assess coronary artery bypass graft anastomoses by providing on-line short-axis (cross-sectional) and longitudinal two-dimensional images of the vessels. To validate measurements of anastomoses with high-frequency epicardial echocardiography, luminal diameter determined by high-frequency epicardial echocardiography was compared with that determined histologically after perfusion fixation in 12 dogs studied after coronary artery bypass grafting.
Whereas the above paper discusses evaluation of vessels and bypass graft anastomoses, the paper does not satisfactorily provide a method which is applicable to clinical use in a hospital environment. Therefore inventor of the present invention has appreciated that an improved method for evaluating flow properties of vessels is of benefit, and has in consequence devised the present invention.